1. Field of the Invention
This invention is in the field of LP cylinder valves and more specifically, methods and tools for effecting a seal between the valve and a stem connected to the outlet of a valve.
2. Description of the Prior Art
A standard valve has been adopted in the LP gas cylinder industry for controlling the flow of LP gas from the cylinder tank. The valve, commonly referred to as a POL fitting, has a bottom threaded portion which is mounted into the LP cylinder tank. The valve also includes an internally threaded outlet with means provided within the valve body to control the flow of LP gas from the tank and through the chamber to the outlet of the valve. In addition, a safety mechanism is provided on the valve to allow escape of LP gas in the event that the pressure within the tank exceeds a predetermined value.
The outlet of the valve includes an internally threaded tube having an inner tapered portion opening into a chamber within the valve body. The outlet of the valve is connected to an external pipe by means of a hollow stem having an inner enlarged bullet shaped end forced into contact with the tapered inner portion of the outlet. The metal contact therefore provides a seal between the outlet and stem. Such a stem is referred to commonly as a hard nosed male connector. Such connectors cost approximately 85.cent. per unit. An alternate version is identical with the hard nosed male connector with the exception that an O-ring is mounted to a groove provided in the enlarged bullet shaped end of the stem thereby preventing metal to metal contact between the bullet shaped end and the outlet with the O-ring being forced between and against the enlarged bullet shaped end and the tapered portion of the outlet. The O-ring is positioned within the tapered portion. Such a connector is commonly referred to as a soft nosed male connector and may be purchased for approximately $5.00 per unit.
The soft nosed male connector is advantageous in that the connector may be repetitively connected and disconnected from the LP gas valve without damage or marring resulting from the metal to metal contact between the enlarged end of the stem and the tapered portion of the valve. A disadvantage of the soft nosed connector is the relative higher cost as compared to the hard nosed male. The soft nosed connector is also advantageous over the hard nosed connector since less torque is required to effect the seal with the O-ring version thereby alleviating the necessity for large wrenches for installing the soft nosed connector.
As a result of the lower cost of the hard nosed connector, most connectors in use are of the hard nosed variety. Disclosed herein is a seal and method for converting a hard nosed connector into a soft nosed connector by inserting an O-ring between the enlarged bullet shaped end of the stem and the tapered portion of the outlet of the valve thereby preventing the metal contact even though a seal is achieved. Also disclosed is a wrench for tightening the connector which includes means for storing spare O-rings within the wrench.